# Brachyponera chinensis

Brachyponera chinensis, the Asian needle ant, is a ponerine ant native to areas of Japan and Asia. Previous known as the Pachycondyla chinensis, which was used in many scientific publications until 2014. The Asian needle ant was introduced to the United States in the 1930's, where it is considered an adventive and possibly invasive species. The Asian needle ant and the Argentine ant (Linepithema humile) have been battling for territory in the U.S. It is documented the Brachyponera chinensis have invaded North America primarily on east coast from Florida to Massachusetts. The range of Asian needle ant extends westward to Kentucky, Tennessee, and Arkansas.Sightings have been confirmed in Washington and Wisconsin, where outliers populations has been established. This invasive species is of growing concern due to ecological impacts on biodiversity and medical risks to human health, via sting-induced anaphylaxis.

## Habitat and Biology

The Asian needle ant thrives in moist and shaded environments. The Brachyponera chinensis is commonly found in agricultural land such as rice-patty dykes in its native range. The Asian needle ant frequently makes ground nests in natural forests preferably beneath stones, logs, or debris. Brachyponera chinensis tend to occupy nests near termite colonies, as termites are a reliable food source. Additionally, this species has also been found to inhabit urban areas in places such as backyards or sidewalks.

## Behavior and Social structure

Brachyponera chinensis exhibits eusociality, with overlapping generations and division of labor within the colony. The queen ant's primary role is for reproduction, while the worker ants help to forage to preserve the colony. Worker ants lack reproductive organs and cannot reproduce. Queen ants have a special pouch to store male sperm that allows them to mate once and continually reproduce over their lifespan.
During emigration of nesting sites, Brachyponera chinensis split into groups to tend to the categories of scouting for new nest locations, queen-tending, and tending to the colonies off-spring. A recruitment strategy called adult transport is where workers carry nestmates during nest emigration. Unlike many other ant species, the Asian needle ant do not rely on pheromone trail for tandem carrying but instead they likely use visual cues.

## Invasive Potential

Branchyponera chinensis is considered a invasive species due to its adaptability and competitive advantages over native ant species. A pre-adaptive trait this species possesses is the ability to tolerate in-breeding and mitigate the negative effects associated with genetic bottle necks by maintaining heterozygosity levels in colonies. The Asian needle ant was likely introduced via shipping docks and may have been introduced over multiple occasions, which could allow for hybridization.
A study in North Carolina found that Branchyponera chinensis outnumbered all native species in most samples areas. The presence of Branchyponera chinensis was also corelated with a reduction in bio-diversity. Additional research on the ecological impact found the native ant species Aphaenogaster rudis was reduced by 96% in invaded areas containing the Asian needle ant. These disturbances of native communities have cascading effects on a broader range of ecosystem processes.

## Public Health Impact

Studies have found that Branchyponera chinensis negatively impacts public health. Although not aggressive, the Asian needle ant will sting when bothered, which can be painful and leave people in discomfort . Allergic reactions involved with the proteins in the species venom can cause anaphylaxisand in some cases urticaria.
As Branchyponera chinensis continues to invade more urban environments the risk of human encounters will rise overtime. Branchyponera chinensis is commonly mistaken due to similar morphology to other ants, such as Branchyponera luteipes, Branchyponera nigrita, and Branchyponera obscurans. Misidentification of the Asian needle ant can lead to lack of awareness of the consequences of being stung, which could potentially delay proper medical interventions.